Virulence-associated genes in Escherichia coli isolates from poultry with colibacillosis

doi:10.1016/S0378-1135(03)00076-2

Veterinary Microbiology

Volume 94, Issue 2, 1 July 2003, Pages 97-103

https://doi.org/10.1016/S0378-1135(03)00076-2 Get rights and content

Abstract

Avian pathogenic Escherichia coli, the causative agent of colibacillosis, harbors several putative virulence genes. In this study we examined by polymerase chain reaction (PCR) the presence of 16 of those genes in 200 colibacillosis isolates from our region. The seven virulence genes iutA, iss, cvaC, tsh, papC, papG and felA were detected significantly more often amongst colibacillosis isolates than in fecal isolates from healthy birds, thereby confirming their worldwide occurrence and possible pathogenic role in colibacillosis. However, several of those genes were not detected in many colibacillosis isolates, and none of them were detected in 27.5% of those isolates, which suggests that variants of those genes and yet undetected virulence factors should be searched for.

Introduction

Escherichia coli is present in the normal microflora of the intestinal tract and environment of poultry, but certain strains designated as avian pathogenic E. coli (APEC) possess specific virulence factors and are able to cause avian colibacillosis. This disease is a serious problem for the poultry industry, since it causes high economic losses. The most severe manifestation of avian colibacillosis is septicemia, which is characterized by air sacculitis, pericarditis, perihepatitis, and salpingitis (Gross, 1994). Several potential virulence genes were identified in APEC, and their virulence-associated bacterial properties include adherence to the respiratory tract, resistance to the immunological defenses, multiplication under iron-restricted conditions, and production of cytotoxic effects (Dho-Moulin and Fairbrother, 1999).

The main adhesins identified in APEC are F1 fimbriae, whose ability to agglutinate fowl erythrocytes is abolished in a medium containing added mannose, and are thus designated as mannose-sensitive haemagglutinating (MSHA), P fimbriae, which represent the main group of mannose-resistant (MR)-fimbriae associated with human urinary tract infections, and AC/I fimbriae, which do not agglutinate red blood cells, but do adhere to avian tracheal cells (Vidotto et al., 1997, Babai et al., 2000). AC/I fimbriae constitute a new member of the group of S-fimbriae (Babai et al., 1997). Other adhesins were also detected in APEC, such as curli fibers, thin aggregative surface fibers, and temperature-sensitive hemagglutinin (Tsh), the latter being a member of the autotransporter group of proteins (Dozois et al., 2000, Maurer et al., 1998). Colicin V, K1 capsular antigen and outer membrane proteins (OMPs) Iss have been associated with resistance to complement, and appear to be important contributors to the virulence of avian E. coli (Dho-Moulin and Fairbrother, 1999). These bacteria also express high affinity iron uptake systems, which are comprised by the siderophore aerobactin (iuc genes) and its outer membrane receptors (iutA) (Vidotto et al., 1994). However, the pathogenesis and the role of virulence factors in colibacillosis have not yet been completely elucidated, which makes its control more difficult (Foley et al., 2000).

The objective of this study was to examine colibacillosis isolates from our region for the presence of virulence-associated genes previously detected in several other countries.

Section snippets

Bacterial strains

Two hundred E. coli strains were isolated from either the tracheal secretion or the liver of 200 chickens with clinical signs of colibacillosis, from different poultry farms; 50 isolates from feces of 50 healthy chickens were used as controls. All isolates were stored at −20 °C in Luria–Bertani (LB) broth to which 15% glycerol was added after growth.

The reference E. coli strains RS218 and V27 (Johnson and Stell, 2000), used as positive controls for many factors, were gently supplied by those

Results

Out of the 16 genes probed by PCR, the genes afa/draBC, sfaDE, sfaS, facA, cnf1 and cnf2 were not found in any of the E. coli isolates. The curli csgA and fimH genes were found in almost all colibacillosis-derived and fecal isolates. Seven genes were detected significantly more often in colibacillosis-derived than in fecal isolates (Table 2). None of the virulence-associated genes investigated were found in 55 (27.5%) of the colibacillosis-derived isolates.

The combination of

Discussion

The seven virulence genes, iutA, iss, cvaC, tsh, papC, papG, and felA were detected significantly more often amongst colibacillosis-derived E. coli isolates than amongst fecal isolates from healthy chickens. These genes were also found in colibacillosis isolates in several countries, and the present results therefore extend and confirm that multiple potential virulence genes participate in the pathogenesis of colibacillosis. However, the frequencies with which some of those genes were detected

Acknowledgements

This work was supported by ‘Conselho Nacional de Desenvolvimento Cientı́fico e Tecnológico’ (CNPq). We are grateful to Dr. James R. Johnson (Infectious Diseases, VA Medical Center, Minneapolis, USA) for supplying the E. coli strains V27 and RS218.

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Veterinary Microbiology

Abstract

Introduction

Section snippets

Bacterial strains

Results

Discussion

Acknowledgements

References (20)

Virulence patterns from septicemic Escherichia coli O78 strains

FEMS Microbiol. Lett.

Polymerase chain reaction for detection of Escherichia coli strains producing cytotoxic necrotizing factor type 1 and type 2 (CNF1 and CNF2)

J. Microbiol. Meth.

Virulence-associated genes in avian pathogenic Escherichia coli (APEC) isolated from internal organs of poultry having died from colibacillosis

Int. J. Med. Microbiol.

Colonization ability and pathogenic properties of an fim—mutant of an avian strain of Escherichia coli

Res. Microbiol.

Virulence mechanisms of avian fimbriated Escherichia coli in experimentally inoculated chickens

Vet. Microbiol.

Adherence pili of pathogenic strains of avian Escherichia coli

Vet. Microbiol.

New fimbrial gene cluster of S-fimbrial adhesin family

Infect. Immun.

Avian pathogenic Escherichia coli (APEC)

Vet. Res.

pap- and pil-related DNA sequences and other virulence determinants associated with Escherichia coli isolated from septicemic chickens and turkeys

Infect. Immun.

Relation between the Tsh autotransporter and pathogenicity of avian Escherichia coli and localization and analysis of the tsh genetic region

Infect. Immun.

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Development of multiplex PCR for rapid and simultaneous detection of E. coli (APEC), Salmonella, Mycoplasma gallisepticum and Mycoplasma Synoviae

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The role of silver nanoparticles in the reluctance of colisepticemia in broiler chickens

Serogrouping, phylotyping, and virulence genotyping of commensal and avian pathogenic Escherichia coli isolated from broilers in Hamedan, Iran

Molecular Identification of Resistance and Pathogenicity Genes of E. coli Isolated From Broiler Chicken Farms

Unveiling Antibiotic Resistance, Virulence, and Molecular Detection of Enteric Bacterial Infections in Broilers: A Study in Egypt